RuboCop WaitFor

Just install the rubocop-wait_for gem

gem install rubocop-wait_for

or if you use bundler put this in your Gemfile

gem 'rubocop-wait_for', require: false

You need to tell RuboCop to load the WaitFor extension. There are two ways to do this:

Put this into your .rubocop.yml.

plugins:
  - rubocop-other-extension
  - rubocop-wait_for

Now you can run rubocop and it will automatically load the RuboCop WaitFor cops together with the standard cops.

rubocop --plugin rubocop-wait_for

RuboCop::RakeTask.new do |task|
  task.plugins << 'rubocop-wait_for'
end

rubocop-wait_for introduces the WaitFor/ConditionMet cop, which scans source comments for wait-for directives:

# wait-for Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.4.0')
some_code_to_remove_once_ruby34_is_in_use()

If the condition inside the comment evaluates to true at the time of linting, RuboCop registers an offense.

This enables workflows like:

• Automatically flagging feature-flagged code once the feature is launched.

• Alerting when temporary code should be deleted (e.g. after a given date or version).

• Monitoring environment-specific conditions in CI pipelines.

Another situation this cop might be useful in is checking gem version.

You can achieve it by using a special form of the magic comment:

# wait-for gem-version rails '>= 8.1'

This condition evaluates to true when the detected Rails version is at least 8.1.

Also, you can do the same with Ruby version using the ruby-version syntax:

# wait-for ruby-version '> 3.4'

Note that gem versions are determined statically using RuboCop’s built-in feature.

You can also use multiple version requirements:

# wait-for gem-version rails '>= 8.1' '< 8.4'
# wait-for ruby-version '>= 3.4' '< 3.4.6'

1. Missing dependencies

   RuboCop does not automatically load project dependencies from your Gemfile.lock. If your condition relies on gems like Rails, you may need to require them manually:

   # wait-for require 'rails'; defined?(::Rails.some_new_feature) != nil
   some_code_to_remove_once_new_rails_feature_is_available()

2. Caching

   Since rubocop-wait_for depends on RuboCop’s caching mechanism, offenses might not be reported until the cache is invalidated — for instance for dynamic conditions like time-based checks.

   You can force cache invalidation by passing RUBOCOP_WAIT_FOR_CHECK_ALL=1 environment variable:

   RUBOCOP_WAIT_FOR_CHECK_ALL=1 bundle exec rubocop --only WaitFor/ConditionMet

rubocop-wait_for is MIT licensed. See the accompanying file for the full text.